Comment 4 for bug 1373495

If HOME is removed, then e.g. vim, bash, etc., will use /root/.vimrc, /root/.bashrc, etc rather than the user's ~/.vimrc, ~/.bashrc, etc. While it's a bad idea to run X clients via sudo, they too would likely look in the wrong locations for configuration files, and there's a chance that X11 clients may not even be able to connect to the X11 server if they are aimed at the wrong .Xauthority file.

Thanks